Abundance and biological effects of microplastics in large rivers

Although marine plastic litter receives a tremendous public and political attention, there is a lack of knowledge on the fate and impact of plastics in freshwater ecosystems (Wagner et al., 2014). This is especially true for microplastics (MP), small plastic fragments designed as such (resin pellets, microbeads from cosmetics) or originating from the degradation of larger plastic items.

Filling the gaps in our knowledge on freshwater MP is crucial to evaluate the environmental impact and potentially take mitigation measures. This is why the German Federal Institute of Hydrology initiated a research project, to investigate and assess

1) the abundance of MP in German rivers,

2) the qualitative and quantitative input of MP in inland waters,

3) the potential of MP to bioaccumulate,

4) the effects of MP exposure in aquatic invertebrates,

5) the environmental impacts of MP.

In this project, we are studying the presence of MP in river sediments and during wastewater treatment using density separation and spectroscopic/metric methods. To determine the bioaccumulation on MP, we perform uptake studies with selected aquatic key species (Chironomus riparius, Daphnia magna, Gammarus pulex, Lumbriculus variegatus, Physella acuta, Sphaerium corneum). Based on this, we will investigate the chronic toxicity of MP in selected invertebrates. To assess whether MP acts as vector for other pollutants, we will also study combined the effects of MP and typical freshwater pollutants. We will ultimately use the data generated within the project to perform a risk assessment of freshwater microplastics.